Generally, GaN-based compound semiconductors are grown on a sapphire substrate, the crystal structure and lattice parameter of which are similar to those of the semiconductors, by epitaxial growth in order to reduce crystal defects. However, the epitaxial layers grown on the sapphire substrate contain many crystal defects such as V-pits, threading dislocations, and the like. When static electricity of high voltage is applied to the epitaxial layers, current is concentrated on crystal defects in the epitaxial layers, thereby promoting breakdown of a diode.
Recently, application of high brightness-high output light emitting diodes (LEDs) is increasing from backlight units of LED TVs to luminaires, automobiles, electric display boards, facilities, and the like. Thus, further improved electrostatic discharge (ESD) protection for light emitting devices is required in the art.